Cannot list restricted files with publishing API

[Fathi Boudra]

With publishing API, a file can be downloaded using:
<server>/path/to/store/file?key=<key>

It assumes we know the file name. However it isn't the case with restricted builds.

Using the key,we need a way to list files , then we can specify which file to download.
Or request to download all the files to avoid to specify a file name.

In both case, we need to extend the API.

[Milo Casagrande (milo)]

Marking as opinion for now, if we do not come up with a different architecture.